Lamp base



Feb. 18, 1941. A. E. BORTON LAMP BASE Filed Dec. 5, 1939 INVENTOR. Bar-011,

Patented Feb. 18, 1941 LAMP BASE Alwyn E. Berton, South Orange, N. J assignor to Associated Patentecs, Inc., Ampere, N. J a corporation of New Jersey Application December 5, 1939, Serial No. 307,593

2 Claims.

The invention here disclosed relates to lamp bases of the type provided with projecting pins for engagement in bayonet slots in a supporting socket and is a continuation in part of patent application Ser. No. 243,753 filed Dec. 3, 1938.

Objects of the invention are to provide the ferrule or shell portion of such a lamp base, including the bayonet pins, all as a single integral element made up out of thin sheet metal strip stock, reinforced in the making, to possess the necessary strength and rigidity for the handling it will receive and so constructed also to effect a full and complete interlock between the shell and the insulating compound which, in the finished article,

it contains.

of the claims.

Fig. 1 is a side view of one of the lamp base shells.

Fig. 2 is a perspective view of such a base on a completed lamp.

Fig. 3 is an enlarged longitudinal sectional view of the base shell, such view being taken on substantially the plane of line 3-3 of Fig. 4.

Fig. 4 is a transverse sectional view as on line &---4 of Fig. 3.

The lamp base ferrule or shell illustrated, consists of a single length of sheet metal strip having its ends joined together by a lock seam 5, which as most clearly shown in Fig. 4, is pressed within the cylindrical outline of the tubular article, thus to leave the shell with a smooth cylindrical outer surface which will slip freely and rotate easily within the lamp socket intended to receive it and which by reason of its inward protrusion will form a key interlocking securely with the compound 6, filling the shell in the completed article.

As shown in Fig. 3, the lock seam does not extend the full width of the strip, or the full length of the tubular shell, leaving unconnected edges at the top at 1, providing a notch for soldering the filament connection at 8, Fig. 2, and facilitating the spreading action in flanging the upper edge' of the shell outwardly at 9, to form a tapered seat for the lamp globe Ill.

The unconnected edges at the lower end of the seam at H, facilitate the inward flanging of the lower end of the shell at [2. This inwardly directed flange encloses and forms a protecting edge over the rim of the enclosed compound.

As disclosed in the patent application above identified, the strip from which the tubular shell is formed may be cut back at the edges, beyond those portions which are engaged to form the lock seam, so that the unconnected edge portions at l 10 and I I will abut or be so related as desired in the finished product, outwardly flanged at the one end and inwardly flanged at the other end. In practice, it is usually desirable to have the outwardly flared edges meet to the extent of providing a notch I, for soldering the filament wire and the other edges meeting at H, in fully abutting engagement as a substantially continuous annular flange.

Another special advantage in making the sleeve of flat strip stock is that prior to bending and. connecting the same in the tubular formation, the then flat stock can be punched in a succession of steps to extrude the sharply angled substantially cylindrical hollow pin projections I3. These hollow protrusions stand at opposite sides of the lock seam, where they will receive and interlock with keying portions of the compound at opposite sides of that part keyed by the seam and relatively close to the part of the compound confined by the lower flange l2. The compound is thus securely keyed and held in the shell at a number of points, so that any strain is distributed, and any possibility of the compound coming loose in the shell is practically eliminated. This multiple keying effect also largely takes care of any expansion or shrinkage from varying temperature conditions.

The gradual drawing of the metal in the several steps disclosed in the patent application, to build out sharply angled pin protrusions, strengthens the material at these points, so that these pins will not break off under hard usage even with thin gage metal.

' In present manufacture, the outwardly flared edge 9, is flanged on the flat stock as disclosed in the patent application before the stock is rolled about the forming mandrel and the other, annular flange I2, is spun on the lower end of the tubular formation while held on the forming mandrel. The working of the metal in the tubular formation in this spinning action strengthens and reinforces the tubular structure. The doubled interlock seam provides desirable longitudinal stiffening and reinforcement. Thus the structure is fully reinforced, both circularly and longitudinally and to such an extent as to make it possible to use light inexpensive strip metal stock and to provide in the end a light weight shell which will be strong and durable and capable of standing all the strains to which it may be subjected.

What is claimed is:

1. As a new article of manufacture, a lamp base ferrule, comprising a length of strip metal rolled in cylindrical form and having the ends of the same secured together by a lock seam indented within the outline of the cylindrical formation in an inwardly projecting key longitudinally reinforcing said formation and opposite Walls of said formation at opposite sides of said indented lock seam being extended in angularly projecting hollow integral pins and the edges of the strip material at opposite ends of the indented lock seam being disconnected and flanged outwardly and inwardly of the cylindrical structure.

2. As a new article of manufacture, a lamp base shell, consisting of a single length of sheet metal rolled into substantially cylindrical formation and having edge portions of less length than the intermediate portion of said strip, said shorter edge portions being unconnected and flanged inwardly of the substantially cylindrical article and said longer intermediate portions being connected by a seam displaced inwardly of the substantially cylindrical contour of the article, the edge portions at the opposite end of the article also being shorter than said intermediate seamed portion and flanged outwardly and leaving opposing portions of the same separated by a notch to receive a filament connection.

ALWYN E. BORTON. 

